A fourth generation (4G) wireless network is an all Internet protocol (IP) wireless network in which different advanced multimedia application services (e.g., voice over IP (VoIP) content, video content, etc.) are delivered over IP. 4G wireless networks include a radio access network, such as, for example, a long term evolution (LTE) network or an enhanced high rate packet data (eHRPD) network. 4G wireless networks also include an IP multimedia subsystem (IMS) network and a wireless core network, referred to as an evolved packet core (EPC) network. The LTE network is often called an evolved universal terrestrial radio access network (E-UTRAN). The EPC network is an all-IP packet-switched core network that supports high-speed wireless and wireline broadband access technologies. An evolved packet system (EPS) is defined to include the LTE (or eHRPD) network and the EPC network.
The EPS may include a packet data network (PDN) gateway (PGW), a serving gateway (SGW), a home subscriber server (HSS), and a mobility management entity (MME). The PGW is provided in the EPC network and provides connectivity of user equipment (UE) to external PDNs by being a traffic exit/entry point for the UE. The SGW is provided in the EPC network, routes and forwards user data packets, and acts as a mobility anchor for a user plane during inter-eNodeB (eNB) handovers. The HSS is provided in the IMS network and includes a database where UE subscriber profile information is stored. The MME is provided in the EPC network and is responsible for handling control plane signaling with UEs as the UEs are provided access to different PDNs.
With the deployment of large amounts of small cells, such as micro cells or pico cells, in a cellular network, traditional network architecture may be more tightly integrated to maximize network efficiency. However, the traditional network architecture is designed in a centralized fashion for core network elements, such as the PGW, the SGW, and the MME. Such core network elements are limited in deployment within the core network (e.g., the EPC network), which creates undesired latency and complications due to long backhauls.
In one example centralized network architecture, a centralized base station can be connected to distributed remote radio heads (RRHs) through high-capacity transport backhauls, such as optical fiber. The centralized network architecture may be an attractive deployment option from a capacity perspective, but requires the availability of expensive high-capacity transport backhauls. In locations where high-capacity transport backhauls are not available or are not economically justifiable, the centralized network architecture may be maintained through an Ethernet operation, administration, and maintenance (OAM) interface or an X2 interface. However, such an arrangement is unable to maximize network capacity since the arrangement only permits long term feedback and coordination for functions. Without real-time feedback from a UE, such as reference signal received power (RSRP) and reference signal received quality (RSRQ) feedback, the capacity of such an arrangement is greatly diminished.